Auxiliary power generation and cooling systems on liquid hydrogen fueled aircraft

ABSTRACT

A hydrogen fueled power system of a vehicle includes a liquid hydrogen fuel source having a volume of liquid hydrogen fuel and a thermal engine configured to expand the liquid hydrogen fuel into gaseous form via interaction between a heated first portion of the hydrogen fuel and a second portion of the hydrogen fuel. A heat exchanger is positioned between the liquid hydrogen source and the thermal engine, and is configured to heat the first portion of the hydrogen fuel via thermal energy exchange with a relatively warm fluid. A turbine is located fluidly downstream of the heat exchanger and upstream of the thermal engine, and is driven by the heated first portion. A power generator is located fluidly downstream of the thermal engine. The power generator utilizes exhaust from the thermal engine to generate electrical or mechanical power. A compressor is operably connected to and driven by the turbine.

BACKGROUND

Exemplary embodiments pertain to the art of hydrogen fueled vehicles, such as aircraft. Hydrogen fueled vehicles, such as aircraft, utilize hydrogen fuel in a fuel cell or combustion engine to provide primary power to the vehicle. The hydrogen is stored in liquid phase at about 20 degrees Kelvin, and for use in a fuel cell should be brought from the storage temperature to a temperature of 300 degrees Kelvin or higher. In such warming of the liquid hydrogen, it would be desirable to utilize excess energy already within the system and prevent waste of such energy.

BRIEF DESCRIPTION

In one embodiment, a hydrogen fueled power system of a vehicle includes a liquid hydrogen fuel source having a volume of liquid hydrogen fuel and a thermal engine configured to expand the liquid hydrogen fuel into gaseous form via interaction between a heated first portion of the hydrogen fuel and a second portion of the hydrogen fuel. A heat exchanger is positioned between the liquid hydrogen source and the thermal engine. The heat exchanger is configured to heat the first portion of the hydrogen fuel via thermal energy exchange with a relatively warm fluid. A turbine is located fluidly downstream of the heat exchanger and upstream of the thermal engine, the turbine driven by the heated first portion of the hydrogen fuel. A power generator is located fluidly downstream of the thermal engine. The power generator utilizes exhaust from the thermal engine to generate electrical or mechanical power. A compressor is operably connected to the turbine. The turbine drives operation of the compressor.

Additionally or alternatively, in this or other embodiments the compressor compresses an airflow for an environmental control system (ECS) of the vehicle.

Additionally or alternatively, in this or other embodiments the compressor is operably connected to the turbine via an electrical generator.

Additionally or alternatively, in this or other embodiments a power storage unit is operably connected to the electrical generator.

Additionally or alternatively, in this or other embodiments the relatively warm fluid is lubricant circulated from the electrical generator.

Additionally or alternatively, in this or other embodiments a pump circulates the lubricant from the electrical generator.

Additionally or alternatively, in this or other embodiments a fluid separator is positioned between the heat exchanger and the turbine to remove condensate from the first portion of the hydrogen fuel.

Additionally or alternatively, in this or other embodiments the power generator is a fuel cell.

Additionally or alternatively, in this or other embodiments the second portion of the hydrogen fuel is exhausted from the thermal engine at 300 degrees Kelvin or more.

In another embodiment, a method of operating a hydrogen fueled power system includes flowing a first portion of hydrogen fuel from a liquid hydrogen fuel source to a heat exchanger, warming the first portion of hydrogen fuel via thermal energy exchange with a relatively warm fluid at the heat exchanger, generating electrical power via the warmed first portion of hydrogen fuel and utilizing the generated electrical power to drive a compressor. The compressor compresses an airflow for an environmental control system (ECS) of the vehicle. The method further includes directing the warmed first portion of hydrogen fuel through a thermal engine, injecting a second portion of hydrogen fuel, cooler than the first portion, into the thermal engine, exhausting gaseous hydrogen from the thermal engine via operation of the thermal engine, and directing the exhaust gaseous hydrogen to a power generator located fluidly downstream of the thermal engine. The power generator utilizes the gaseous hydrogen to generate electrical or mechanical power.

Additionally or alternatively, in this or other embodiments the warmed first portion of hydrogen fuel is flowed through a turbine to drive rotation of the turbine before directing the warmed first portion through the thermal engine.

Additionally or alternatively, in this or other embodiments the electrical power is generated via an electrical generator operably connected to the turbine via rotation of the turbine.

Additionally or alternatively, in this or other embodiments lubricant from the electrical generator is circulated through the heat exchanger to warm the first portion of hydrogen fuel.

Additionally or alternatively, in this or other embodiments liquid phase hydrogen fuel is removed from the heated first portion of the hydrogen fuel prior to entering the turbine via a separator located between the heat exchanger and the turbine.

Additionally or alternatively, in this or other embodiments the heat exchanger is operated as a distiller.

Additionally or alternatively, in this or other embodiments the power generator is a combustor, and the distiller outputs a flow of oxygen-enriched air for use at the combustor.

Additionally or alternatively, in this or other embodiments the power generator is a fuel cell.

BRIEF DESCRIPTION OF THE DRAWINGS

The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike:

FIG. 1 is a schematic illustration of an embodiment of a hydrogen fueled power system;

FIG. 2 is a schematic illustration of an embodiment of a hydrogen fueled power system including a turbine and generator;

FIG. 3 is a schematic illustration of an embodiment of a hydrogen fueled power system including a compressor;

FIG. 4 is a schematic illustration of another embodiment of a hydrogen fueled power system;

FIG. 5 is a schematic illustration of an embodiment of a hydrogen fueled power system including a distiller;

FIG. 6 is a schematic illustration of an embodiment of a liquid hydrogen storage tank; and

FIG. 7 is a schematic illustration of yet another embodiment of a power system.

DETAILED DESCRIPTION

A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures.

Referring now to FIG. 1 , illustrated is a schematic of an embodiment of a hydrogen-fueled power system 10. Hydrogen fuel 12 is stored in liquid phase in a hydrogen tank 14 at, for example, a temperature of 20 degrees Kelvin or less. The hydrogen fuel 12 flows from the hydrogen tank 14, and a first fuel portion 12 a is directed through a heat exchanger 16 where it is warmed via thermal energy exchange with a heat transfer fluid 18 from a heat source. The heated first fuel portion 12 a is then directed to a thermal engine 20 as gaseous hydrogen. A second fuel portion 12 b, which as liquid hydrogen is much colder than the first fuel portion 12 a, is injected into the thermal engine 20 from the hydrogen tank 14. The liquid hydrogen second fuel portion 12 b is rapidly expanded at the thermal engine 20 and is exhausted as gaseous hydrogen fuel 12 from the thermal engine 20 at, for example, 300 degrees Kelvin or more. The gaseous hydrogen fuel 12 is then utilized for power generation at, for example, a fuel cell 22. While a fuel cell is discussed and shown in FIG. 1 , one skilled in the art will readily appreciate that alternative power generation means, such as combustion, may be utilized. Further, in some embodiments and intermediate working fluid, such as gaseous hydrogen or nitrogen, may be utilized to transfer thermal energy between the first fuel portion 12 a and the second fuel portion 12 b.

Referring now to FIG. 2 , the thermal energy at the heat exchanger 16 may be utilized in several ways. In the embodiment of FIG. 2 , before flowing to the thermal engine 20, the heated first fuel portion 12 a is flowed from the heat exchanger 16 through a turbine 24 to drive rotation of the turbine 24 and expand the heated first fuel portion 12 a. From the turbine 24, the heated first fuel portion 12 a is flowed to the thermal engine 20. In some embodiments, a fluid separator 60 is located between the heat exchanger 16 and the turbine 24 to remove any condensate or liquid in the first fuel portion 12 a before it reaches the turbine 24.

The turbine 24 is connected to an electrical generator 26 and drives the generator 26 to generate electrical power, which may be utilized to power various components 28 connected to the generator 26 either directly or via a power storage unit such as a battery 30. The generator 26 has a volume of lubricant such as oil to lubricate the generator 26. This flow of oil 32 is directed to the heat exchanger 16 via pump 34, where the flow of oil 32 exchanges thermal energy with the first fuel portion 12 a to expand the first fuel portion 12 a and cool the flow of oil 32 before the flow of oil 32 is returned to the generator 26.

In another embodiment, illustrated in FIG. 3 , the system 10 includes a compressor 64 connected to the generator 26, which may also be operated as a motor to drive the compressor 64, which may be the compressor for the environmental control system (ECS) of the vehicle or aircraft. The compressor 64 compresses an airflow 36 from an air source, for example, ambient, and directs the compressed airflow 36 to the ECS 38. Referring now to FIG. 4 , a cooling loop 40 using non-freezing working fluids such as Helium, Neon, or Hydrogen is connected to the heat exchanger 16 from one or more other vehicle components such as motors, electronics, oil system or the ECS 38, The cooling loop 40 provides cooling to the one or more vehicle components, and at the heat exchanger 16 exchanges thermal energy with the first fuel portion 12 a to heat the first fuel portion 2 a before the first fuel portion 12 a is directed to the thermal engine 20.

Referring now to FIG. 5 , the heat exchanger 16 may be operated as a distiller 42. The distiller utilizes the first flow of fuel 12 a and a flow of air 44 to provide oxygen enriched air 46 and nitrogen enriched exhaust 48 as will as the heated first fuel portion 12 a. The gaseous heated first fuel portion 12 a is directed to the thermal engine 20, which in systems 10 where the power generation means is combustion, the oxygen enriched air 46 is flowed to a combustor for combustion with the flow of fuel 12.

Referring now to FIG. 6 , illustrated is an embodiment of a hydrogen tank 14. The hydrogen tank 14 surrounds the hydrogen fuel 12 with one or more thermal insulating layers. In one embodiment, such as illustrated in FIG. 6 , the one or more insulating layers includes two vacuum insulating layers 52, with a methane insulating layer 54 between the vacuum insulating layers 52. The methane insulating layer 54 has a boiling point of 116 degrees Kelvin, and may be utilized for combustion if needed.

As shown in FIG. 7 , in some embodiments the insulating layer 54 is also a liquid fuel, which may be combusted with the hydrogen fuel 12 stored in the hydrogen tank. The insulating layer 54 is for example, methane or a renewable fuel having a low boiling temperature. This insulating layer 54 may be processed similar to the hydrogen fuel 12 as in FIGS. 2 and/or 3 . For example, as shown in FIG. 7 a first insulating layer portion 54 a through the heat exchanger 16 where it is warmed via thermal energy exchange with the heat transfer fluid 18 from a heat source. The heated first insulating layer portion 54 a is then directed to a thermal engine 20 as gaseous hydrogen. A second insulting layer portion 54 b, which as liquid insulating layer material is much colder than the first insulating layer portion 54 a, is injected into the thermal engine 20 from the hydrogen tank 14. The liquid second insulating layer portion 54 b is rapidly expanded at the thermal engine 20 and is exhausted as gaseous insulating layer material 54 b from the thermal engine 20 at, for example, 300 degrees Kelvin or more. The insulating layer material 54 b is then utilized for power generation at, for example, a fuel cell 22 a. While a fuel cell is discussed and shown in FIG. 7 , one skilled in the art will readily appreciate that alternative power generation means, such as combustion, may be utilized.

Utilization of the thermal energy of the hydrogen fuel 12 when heating the first fuel portion 12 a can provide an additional onboard power supply, reducing overall power consumption and improve hydrogen-powered vehicle efficiency. The cooling capacity of the liquid hydrogen fuel provides either in cooling to either in flight ECS or Oxygen/Nitrogen enrichment of air for combustion. The use of enriched airflow for combustion may increase combustion efficiency by up to 15%.

The term “about” is intended to include the degree of error associated with measurement of the particular quantity based upon the equipment available at the time of filing the application.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, element components, and/or groups thereof.

While the present disclosure has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present disclosure without departing from the essential scope thereof. Therefore, it is intended that the present disclosure not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this present disclosure, but that the present disclosure will include all embodiments falling within the scope of the claims. 

What is claimed is:
 1. A hydrogen fueled power system of a vehicle, comprising: a liquid hydrogen fuel source having a volume of liquid hydrogen fuel; a thermal engine configured to expand the liquid hydrogen fuel into gaseous form via interaction between a heated first portion of the hydrogen fuel and a second portion of the hydrogen fuel; a heat exchanger disposed between the liquid hydrogen source and the thermal engine, the heat exchanger configured to heat the first portion of the hydrogen fuel via thermal energy exchange with a relatively warm fluid; a turbine disposed fluidly downstream of the heat exchanger and upstream of the thermal engine, the turbine driven by the heated first portion of the hydrogen fuel; and a power generator disposed fluidly downstream of the thermal engine, the power generator utilizing exhaust from the thermal engine to generate electrical or mechanical power; a compressor operably connected to the turbine, wherein the turbine drives operation of the compressor; and a fluid separator disposed between the heat exchanger and the turbine to remove condensate from the first portion of the hydrogen fuel.
 2. The power system of claim 1, wherein the compressor compresses an airflow for an environmental control system (ECS) of the vehicle.
 3. The power system of claim 1, wherein the compressor is operably connected to the turbine via an electrical generator.
 4. The power system of claim 3, wherein the relatively warm fluid is lubricant circulated from the electrical generator.
 5. The power system of claim 4, further comprising a pump to circulate the lubricant from the electrical generator.
 6. The power system of claim 1, wherein the power generator is a fuel cell.
 7. The power system of claim 1, wherein the second portion of the hydrogen fuel is exhausted from the thermal engine at 300 degrees Kelvin or more.
 8. A hydrogen fueled power system of a vehicle, comprising: a liquid hydrogen fuel source having a volume of liquid hydrogen fuel; a thermal engine configured to expand the liquid hydrogen fuel into gaseous form via interaction between a heated first portion of the hydrogen fuel and a second portion of the hydrogen fuel; a heat exchanger disposed between the liquid hydrogen source and the thermal engine, the heat exchanger configured to heat the first portion of the hydrogen fuel via thermal energy exchange with a relatively warm fluid; a turbine disposed fluidly downstream of the heat exchanger and upstream of the thermal engine, the turbine driven by the heated first portion of the hydrogen fuel; and a power generator disposed fluidly downstream of the thermal engine, the power generator utilizing exhaust from the thermal engine to generate electrical or mechanical power; a compressor operably connected to the turbine, wherein the turbine drives operation of the compressor; wherein the compressor is operably connected to the turbine via an electrical generator; and further comprising a power storage unit operably connected to the electrical generator.
 9. A method of operating a hydrogen fueled power system, comprising: flowing a first portion of hydrogen fuel from a liquid hydrogen fuel source to a heat exchanger; warming the first portion of hydrogen fuel via thermal energy exchange with a relatively warm fluid at the heat exchanger; generating electrical power via the warmed first portion of hydrogen fuel; utilizing the generated electrical power to drive a compressor, wherein the compressor compresses an airflow for an environmental control system (ECS) of the vehicle; directing the warmed first portion of hydrogen fuel through a thermal engine; injecting a second portion of hydrogen fuel, cooler than the first portion, into the thermal engine; exhausting gaseous hydrogen from the thermal engine via operation of the thermal engine; and directing the exhaust gaseous hydrogen to a power generator disposed fluidly downstream of the thermal engine, the power generator utilizing the gaseous hydrogen to generate electrical or mechanical power.
 10. The method of claim 9, further comprising flowing the warmed first portion of hydrogen fuel through a turbine to drive rotation of the turbine before directing the warmed first portion through the thermal engine.
 11. The method of claim 10, further comprising generating the electrical power via an electrical generator operably connected to the turbine via rotation of the turbine.
 12. The method of claim 11, further comprising circulating lubricant from the electrical generator through the heat exchanger to warm the first portion of hydrogen fuel.
 13. The method of claim 10, further comprising removing liquid phase hydrogen fuel from the heated first portion of the hydrogen fuel prior to entering the turbine via a separator disposed between the heat exchanger and the turbine.
 14. The method of claim 9, further comprising operating the heat exchanger as a distiller.
 15. The method of claim 14, wherein the power generator is a combustor, and the distiller outputs a flow of oxygen-enriched air for use at the combustor.
 16. The method of claim 9, wherein the power generator is a fuel cell. 